Stevenson



Jan. 24, 1956 R. STEVENSON 2,732,450

HYDRO-ELECTRIC SWITCH Filed Oct. 5. 1951 3 Sheets-Sheet 1 /7 V l ,4 E7 2 57 Fl 13. E Fl El 1 7 4 INVENTOR. RUBERT ETEVENEUN ATT URNEY Jan. 24, 1956 STEVENSON 2,732,450

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JNVENTOR. EQ BBERT ETEVENSUN filth. GMAJIM ATTURNEY Jan. 24, 1956 R. STEVENSON 2,732,450

HYDRO-ELECTRIC SWITCH Filed Oct. 6, 1951 3 Sheets-Sheet 3 MACH/NE TOOL PUM?

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RUBERT STEVENSON Jww $1M MW ATTORNEY United States Patent HYnno-ELEcrnic swrrcn Robert Stevenson, Barrington, R. I., assignor to Anon, l ne, a corporation of Rhode Island Application October 6, 1951, Serial No. 25!),h45

3 Claims. (Cl. 20032) This invention relates to hydroelectric switches and more particularly to hydraulic pressure responsive means for actuating an electric switch.

One of the objects of the present invention is to provide means for easily and readily adjusting the differential pressure control in a hydro-electric switch.

Another object of the present invention is to eliminate the necessity of a bleeder return in the hydraulic control mechanism.

Still another object of the present invention is to provide a hydro-electric switch, lighter in weight, having fewer parts, more simple in operation, less costly to manufacture, having a wider range of ditierential pressures, for use in aircraft.

And still another object of the present invention is to provide an arrangement so that when pressure in the system falls below a pro-determined point an electric switch automatically opens or closes an electrical circuit to cause a pump or similar apparatus to function to either build up the pressure in the system, indicate that the wheels are up or down on aircraft, that bomb bay doors are open or closed, that a cutting tool is dull in a machine tool or a safety switch is caused to function in a hydraulic system.

And still another object of the present invention is to provide adjustable means on the hydraulic pressure responsive means.

Other objects of the present invention will become apparent in part and be pointed out in part in the following specification and claims.

The present invention is an improvement over my United States Patent #2,4-85, )74 issued October 18, 1949, for Pressure Control in which the differential in pressure was determined by the size of the conduits running from the valve seats. Said conduits were non-adjustable. in the present invention a mechanical arrangement controls the pressure differential. In addition a single pole double throw switch replaces a simple micro switch. in my patent the hydraulic system was bled or" fluid every time the hydraulic elements caused the electrical switch control to operate. The present mechanical arrangement eliminates that undesirable feature of a hydroelectric switch.

Like reference numerals refer to like parts in the accompanying drawings, in which:

Figure l is a front elevational view of the new hydro electric switch.

Figure 2 is a side elevational view of the same.

Figure 3 is a plan view of the same.

Figure 4 is a sectional view taken along line 4- of Figure 2 looking in the direction of the arrows.

Figure 5 is a sectional view taken along line 5-5 of Figure 4.

Figure 6 is a sectional view taken along line 66 of Figure 4.

Figure 7 is a diagrammatic view showing the application of the present invention to a machine tool.

Figure 8 is a diagrammatic view showing the application of the present invention to a hydraulic pressure system.

With reference to the drawings the hydro-electric switch 3% comprises a pressure tube 19 having a pres- 5 sure chamber 31 provided with screw threads 32 which terminate in an annular groove 33. A cavity 34 adjacent said groove is interconnected by means of a tunnel to a chamber 36 having threads 37 on its upper end. Pressure tube 19 is secured to housing 1 by means of machine screws A plunger pin guide screw 28 T-shaped is provided with screw threads 46 on the outside of its largest diameter. Said threads 46 engage screw threads 32. The shoulder of plunger pin guide screw 23 rests against the base of annular groove 33 while the shank 42 is accommodated in cavity 34. A plunger pin secured to a plunger 2- by means of a grooved pin 2:: passes through a tunnel 35, a passageway 43 in plunger pin guide screw and into pressure chamber o. A dome 44- is placed in the end of plunger pin guide screw 23 Packing or" a usual mafacing pressure Cl'lZlfiliIvc terial, shown as consisting of a neoprene O sealing ring 27 is placed around plunger pin between the base of cavity 3d and the end of shank 1 to provide a fluid tight seal. Plunger is accommodated for slidable its base is in the form of a while its side is arcuate in shape providing a on the end opposite plug 45.

movement in chamber plug 3- and the base screw l7 vari pressure sprin Housing raised sides :33, said s ruin 52 formed by the cover 2 secured to s 7 which are acand 63 formed e. ity and 5i: has a machine screw commodated in tapped holes 6%), 6i, 6

the intersection of said sides. 3 tegrai with si'e 53 provided with a c tion passageway A ten. across pads "75, 1 ing 1 and is se screws 6- formed innduit connecstrip is mounted t or use 66 of housans of machine are secured to t an in said strip micro-switch 3 3.127", Terminal 1%"7. -52 is connected to 2. 1 slides in bushing forming integral part of guide bracket 5 is secur d to base by means of machine s rews 74.

A pivot stud '7 has an enlarged head '75 on one end, and a reduced portion 79 provided with screw threads as in the other end. Cover 2 is provided with an annular recess 77 adapted to accommodate enlarged head "i5 and act as a support for said head '75. Base 66 is provided with a pad on cavity 52 side and with a boss 3% on the outboard side. Boss Si) is counterbored as at 31 to accommodate a washer 33 and a filister screv head 82. Reduced portion 79 rotatably fits in a bearing 83 located in the wall of base 66 between pad 78 and boss 80. Filister head screw 82 accommodating screw threads 76 holds pivot stud 7 in place. A bell crank trip lever 12 is pivotally mounted on pivot stud 7. The short arm 84 of bell crank trip lever 12 is provided with a cam 85 constituting two concentric arcs 35 and 85A with a step 8513 between them. The height of step 355 or the difference between arc 85A and are 85 is sufficient to actuate micro-switch adapter 6 initiating the movement for the functioning of movable contact 72. The long arm $6 of bell crank trip lever 12 is provided with clearance diameter 87 sufliciently large to allow trip lever cap screw 13 to move upwardly through said clearance diameter 37 but sutficiently small to permit the head of trip lever cap screw 13 to force long arm $6 downwardly at the proper time in the cycle presently to be described.

Actuator i1 is bifurcated on one end to provide nearings 98, 91 which straddle trip lever 12 and which are mounted for pivotal movement on pivot stud 7. Bear ings 9t), 91 are held against transverse movement by enlarged head 75 and pad 7;; and thus prevent trip lever 12 from transverse movement.

Actuator 11 is provided with a tapped hole 92 adapted to accommodate trip lever cap screw 13. A U-shaped bracket 93 adapted to accommodate a spring 94 is spot welded to actuator 11. Spring 9-.- urges trip lever 12 away from actuator 11 by pressing against the underside of long arm 86. Actuator spring pin 15 is secured in actuator 11. Actuator spring 16 positioned over spring pin 15 works against actuator 11 on one end and against a projection 55 formed in side 56 on the other end. The end of actuator 11 farthest from the bifurcated bearings 90, 91 bears against contact surface 47. A clearance diameter 96 is provided in pressure tube 12 and side wall 56 to permit actuator 11 to have up and down movement as it pivots on pivot stud 7.

In operation hydro-electric switch 30 will function as follows: The line of a hydraulic pressure system will be connected to screw threads 32. Thereafter fluid under pressure will circulate in pressure chamber 31. So long as the pressure does not exceed the pounds per square inch, pressure setting spring 20 imposes upon plug 45, the parts of the hydro-electric switch will assume the position shown in Figures 4, 5 and 6. Just as soon as the fluid pressure in pressure chamber 31 exceeds the p. s. i. of spring 20, plunger 25 will be forced upwardly by the fluid pressure, carrying plunger 24 with it through grooved pin 26 and plug 45. Side 46 and contact surface 47 will cause actuator 11 to pivot around pivot stud 7 thereby compressing actuator spring 16 and increasing the compression of spring 94 as U-shaped bracket 93 moves upwardly with actuator 11. As trip lever cap screw 13 moves upwardly with actuator 11, trip lever 12 will pivot around pivot stud 7 under the influence of spring 94. Cam 85 will ride over micro-switch adapter 6, depressing movable contact 72 thereby uniting the opening or the closing of the circuit depending upon the setting of micro-switch 3.

By way of further example, referring to Figure 7 wherein is shown diagrammatically, the application of the present hydro-electric switch to a machine tool. The hydraulically operated machine tool functioning normally exerts a predetermined pressure on pressure setting spring 20. As the tool becomes dull, more hydraulic pressure is needed to carry the work table past the dull tool. The pressure will build up in pressure chamber 31 to the point where plunger pin 25 forces plunger 24 against the pressure setting spring 20, so that plunger 24- will pivot actuator 11 around pivot stud 7 and through trip lever cap screw 13 and actuator spring to, spring 94; bell crank trip lever 12 will pivot around pivot stud 7 causing cam 85 to depress micro-switch adapter 6 thereby causing movable contact 72 to function, causing single pole, double throw micro-switch 3 to move from normally open to normally closed thereby causing indicator light 1% to be on, showing the tool to be dull.

In Figure 8 there is shown diagrammatically, another type of application of the present invention to a hydraulically operated system in which a pre-determined pressure is maintained.

The normally closed terminal of the micro-switch 3 allows the electric current to be supplied to the motor operating the pump which produces the pressure in the accumulator tank. When that pressure reaches a pre determined point plungerpin 25 overcoming pressure setting spring 2% will cause plunger 24 to rotate actuator 11 and as previously described trip lever 12 and microswitch 3, thereby throwing the switch contacts to normally open, shutting off the electric current, hence the motor, pump and pressure.

Having shown and described, by way of example, a preferred embodiment of the present invention but not wishing to limit myself to the exact structure shown since structural arrangements are contemplated which would not depart from either the spirit or scope of the advancement made in the art what I claim is:

l. A hydro-electric switch having in combination a housing, a pressure tube secured to said housing, a pressure chamber in one end of said tube, an adjustably mounted pressure setting screw in the other end of said tube, a cavity contiguous with said pressure chamber, a second chamber in said pressure tube, a tunnel connecting said second chamber and said cavity, a plunger pin guide screw secured in said pressure chamber, having a shank extending into said cavity, packing between said shank and the base of said cavity, a plunger pin secured to a plunger passing through the tunnel, packing plunger pin guide screw and extending into said pressure chamber, a dome on said plunger pin guide screw facing said pressure chamber, a spring having one end in said adjustably mounted pressure setting screw, the other end of said spring yieldingly set against said plunger, a clearance diameter in said housing and said pressure tube, a pivot stud mounted in said housing, an actuator having a bifurcated bearing mounted on said pivot stud, the end opposite to the bifurcated bearing yieldingly contacting said plunger and extended through said clearance diameter, an actuator spring pin secured in said actuator, a spring mounted on said actuator spring pin bearing against a projection in said housing, a U-shaped bracket secured to said actuator, a spring mounted in said bracket yieldingly urging a bell crank trip lever pivotally mounted on said pivot stud away from said actuator, a trip lever cap screw mounted in said actuator, passing through a clearance diameter in said trip lever, the head of said cap screw limiting the yielding movement of said spring, an arm of said belt crank trip lever contacting the movable contact of a microswitch.

2. A hydraulic-electric switch having in combination a housing, a pressure tube secured to said housing, a pressure chamber provided with means for attaching said pressure tube to the line of a hydraulic system, a cavity, an annular groove between said cavity and said pressure chamber, a second chamber in said pressure tube provided with screw threads in its upper end, a tunnel connecting said second chamber with said cavity, a plunger pin guide screw T-shaped secured in said pressure chamber with the shank accommodated in said cavity, a passageway throughout its length, a plunger provided with a plug on one end having an arcuate side with a contact surface end located in said second chamber, a plunger secured to said plug by means of a grooved pin, said plunger extending through said tunnel, and said passageway into said pressure chamber, a fluid seal surrounding said plunger located in said cavity, a pressure setting screw having screw threads engageable with screw threads in said second chamber, a hexagonal head on said pressure screw and a bore in the end opposite said head, a lock nut engageable with said screw threads not engaging the screw threads in said pressure tube, a spring extending from said bore to said plug, a clearance diameter in said housing and said pressure tube, a cover having an annular recess secured to said housing, a pad and a boss integrally connected to said housing, a bearing in the wall between said pad and housing, a pivot head having an enlarged head on one end and a reduced portion on the other end engageable in said bearing and secured therein by means of a washer and screw accommodated in a counterbore in said boss, said screw being accommodated in screw threads located in said pivot stud, an actuator provided with a bifurcated bearing pivotally mounted on said pivot stud between said enlarged head and said pad, a U-shaped bracket secured to said actuator, a spring in said bracket, an actuator spring pin fixed in said actuator, chamber in said housing, a base and four sides comprising said housing, one side having a projection, a spring located over said actuator spring pin contacting said actuator and said projection, a tapped hole in said actuator, said actuator contacting said contact surface of said plunger, a bell crank trip lever provided with a long arm and a short arm pivotally mounted on said pivot stud between said bifurcated bearings, said spring in the U bracket contacting said long arm, a clearance diameter in said long arm, a trip lever cap screw in said clearance diameter secured in said tapped hole, a guide bracket secured to said housing having a bushing for slidably mounting a micro-switch adapter, a micro-switch mounting plate secured to said housing, a single pole, double throw micro-switch secured to said mounting plate, pads forming an integral part of said housing, a terminal strip secured to said pads, terminals secured to said terminal strip contacting said micro-switch, a conduit formed in said housing and a passageway in said conduit.

3. A hydroelectric switch having in combination a tube comprising a fluid pressure chamber and a second chamber, means responsive to the fluid pressure in said fluid pressure chamber comprising a second chamber pin, a plunger resiliently mounted in said plunger, means surrounding said plunger pin to form a fluid tight seal, a pivotally mounted actuator resiliently held in engagement with said plunger, 21 pivotally mounted bell crank trip lever yieldingly held in engagement with said actuator, an adjustment between said actuator and said bell crank trip lever controlling the engagement between said actuator and bell crank trip lever, an arm on said bell crank trip lever, an electric switch having a movable contact, said arm engaging, to actuate, said movable contact.

References Cited in the file of this patent UNITED STATES PATENTS 2,196,522 Davis Apr. 9, 1940 2,224,957 Ernst Dec. 17, 1940 2,280,262 Purat Apr. 21, 1942 2,289,108 Eaton July 7, 1942 2,301,613 Canfield Nov. 10, 1942 2,302,923 Zimarik Nov. 24, 1942 2,336,887 Piron Dec. 14, 1943 2,431,674 Baak Dec. 2, 1947 2,437,846 Yeida Mar. 16, 1948 2,452,379 Kasparek Oct. 26, 1948 2,457,467 Hartman Dec. 28, 1948 2,467,509 Trautman Apr. 19, 1949 2,492,261 Bordelon Dec. 27, 1949 2,507,065 Trautman May 9, 1950 2,529,688 Grupp Nov. 14, 1950 2,598,446 Schneider May 27, 1952 

